function [Z_next] = update_Z(X_t, T, At, Bt, Z_last, lambda)
%UPDATE_Z 此处显示有关此函数的摘要
%   此处显示详细说明
Tmp = At*X_t*Bt'*T'+lambda*Z_last;
[Up,Sp,Vp] = svd(Tmp,'econ');
Z_next = Up*Vp';